Colorectal cancer in man is frequently asymptomatic requiring special efforts to be detected, particularly in its early stages. Contamination of the stools with occult blood occurs before visible bloody stools are detected. The early diagnosis of carcinomas of the colon and rectum is therefore aided by the detection of occult blood in the stool.
Procedures for testing for the presence of occult blood in the fecal matter are well known. For example, tests employing specimen slides such as those described in U.S. Pat. No. 3,996,006 are well recognized in the medical art as practicable and rational screening tests for the early detection of colorectal cancer. Briefly, the test consists of using a specimen test slide which employs an absorbent sheet treated with a reagent which gives a color reaction when contacted with blood. The sheet of absorbent paper is sandwiched between a front and rear panel. The front panel has a plurality of openings and a cover for said openings. The rear panel has tab means opposite said openings. An example of such slides are those sold under the trademark of `Hemoccult`.
To use the above noted commercial slides the patient must obtain specimens from different parts of his stool and smear them on the absorbent paper through the openings in the front panel. These feces samples must be removed from a toilet bowl or bed pan on a wooden spatula and then smeared on the absorbent sheet. The tab or flap in the rear panel is opened and a developing solution is applied to the absorbent paper opposite the openings in the front panel. A blue color denotes a positive test, i.e., presence of occult blood in the fecal matter. Because of the inhomogeneity of feces and because gastrointestinal bleeding tends to be intermittent, investigations have shown that a multiplicity of specimens should be tested for optimum results. A random single portion from a stool is not sufficient because the occult blood may be in a portion of the stool not tested. The patient is therefore given slides with, for example, six test sites and instructed to make smears with two separate portions of his stool on three separate days.
Although this test has been well accepted by medical experts as a screening approach for colorectal cancer, it does have several major disadvantages. The test is normally conducted in a physician's office or at a diagnostic laboratory. However, many patients are requested to initiate the test at home and then send the slide to a physician or laboratory for completion and analysis.
One disadvantage is that the patient is faced with the difficult task of making smears from separate portions of his stool. The extreme unpleasantness, inconvenience and difficulty of the test confronting the patient cannot be overstated. Most patients are unaccustomed to handling their stool, particularly when the stool is in a toilet bowl under perhaps six inches of water. Needless to say, many patients become nauseous at the thought of conducting such a test. A further disadvantage is that when the patient initiates the test at home, he must store the fecal specimens of the first two days until he takes his last specimen on the third day. The patient is cautioned to protect the slides from light and heat. The only cool spot available to the average patient would be his refrigerator. It is appparent he would not wish to store his fecal specimens in the family refrigerator.